Stroller Linkage Mechanism for Compact Folding Without Backrest Ground Contact

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Solution Overview

Problem

The backrest of existing strollers often interferes with the folding process, gets dirty, and increases the length of the folded stroller, making storage and transportation less efficient.

Innovation Solution

A transportation device with linkage members that pivotally connect various components, allowing the seat and backrest to rotate in a manner that prevents the backrest from touching the ground during folding, thereby increasing its length and reducing the overall height of the folded device.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the backrest is made longer to provide better support, then the comfort is improved, but the backrest will touch the ground when folded, affecting the folding process and increasing the length of the folded stroller

Engineering Contradiction:
ImprovecomfortVSAvoidlength of folded stroller
Core Design Contradiction:
Ease of operationVSLength of moving object

Solution Approach 1:

The patent applies dynamics by making the seat rotation direction changeable. In the folded state, the seat rotates in a direction that prevents the backrest from touching the ground, while in the unfolded state, it returns to its original position. This dynamic adaptation resolves the contradiction between backrest length and folded stroller length.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the rotation direction parameter of the seat based on the folding state. When folded, the seat rotates in one direction to avoid ground contact, and when unfolded, it rotates in the opposite direction. This parameter change allows the backrest to be longer without increasing the folded length.

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If the backrest is made longer to provide better support, then the comfort is improved, but the backrest is more prone to getting dirty from ground contact

Engineering Contradiction:
ImprovecomfortVSAvoidground contact
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent uses dynamic rotation direction control to prevent the backrest from contacting the ground during folding. By changing the rotation direction based on the folding state, the backrest remains elevated and clean while maintaining its length for comfort.

Inventive Principle:
Principle #15Dynamics

3Device complexity

If the seat and handrail rotate upward when folded, then the folding mechanism is simplified, but the length of the folded stroller increases, making storage and transportation less efficient

Engineering Contradiction:
Improvefolding mechanismVSAvoidlength of folded stroller
Core Design Contradiction:
Device complexityVSLength of moving object

Solution Approach 1:

The patent applies dynamics by making the seat rotation direction changeable. In the folded state, the seat rotates in a direction that prevents the backrest from touching the ground, while in the unfolded state, it returns to its original position. This dynamic adaptation resolves the contradiction between backrest length and folded stroller length.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP4237313B1Transportation device
Publication Date: 2025.09.03 WONDERLAND SWITZERLAND AG
  • EP4237313B1 patent drawingFigure 1
  • EP4237313B1 patent drawingFigure 2
  • EP4237313B1 patent drawingFigure 3

AI summary

A transportation device (3) includes a handle (30), a rear leg (34), a front leg (36), a seat (38), a fixing member (32), a first (40) and a second seat linkage member (42). The front leg (36) is pivotally connected to the rear leg (34). The seat (38) is pivotally connected to the front leg (36). The fixing member (32) is disposed at a rear side (382) of the seat (38) and connected to an end of the handle (30). The first seat linkage member (40) is pivotally connected to the seat (38) and the fixing member (32). The second seat linkage member (42) is pivotally connected to the seat (38) and the rear leg (34). When the handle (30), the rear leg (34) and the front leg (36) are folded with respect to each other, the fixing member (32) and the rear leg (34) drive the rear side (382) of the seat (38) to rotate toward a direction opposite to the ground by the first seat linkage member (40) and the second seat linkage member (42) respectively.